AAP leader Arvind Kejriwal today apologised for his party workers' attack on Bharatiya Janata Party HQs in Delhi and Lucknow while protesting his "detention" and urged them to stick to non-violence.

"It was going to happen...some of them retaliated after they were attacked...I apologise for their behaviour and I once again urge them to remain non-violent," he told reporters here in response to a query on the arrest of over a dozen AAP workers in Delhi.

AAP workers had yesterday clashed with BJP activists outside the saffron party headquarters in Delhi and Lucknow after Kejriwal's car was damaged in Gujarat in retaliation to protests against his brief "detention" in the state.

Yesterday, Kejriwal, who began his four-day tour of Gujarat, was detained for alleged violation of the model code of conduct by travelling in a long carcade. Shortly later, he was allowed to go.

Fourteen AAP members were arrested after Delhi Police registered an FIR in connection with the clashes between supporters of the two parties in the national capital that left 28 people injured.

AAP workers had stormed the BJP head office on Ashoka Road in central Delhi protesting against Kejriwal's 'detention' in Radhanpur in North Gujarat where he has gone to "assess" the development claims made by CM Narendra Modi.

In Lucknow, workers of Aam Aadmi Party, armed with brooms, had clashed with lathi-wielding activists of BJP and fought pitched street battles outside BJP office on Vidhan Sabha Marg in protest against their chief's detention.

Kejriwal during his second day of Gujarat sojourn today, will meet Sikh farmers settled in the state's Kutch district.